The present invention relates to electroconductive proppant compositions and methods of using electroconductive proppant compositions in subterranean formations to determine, among other things, proppant pack characteristics such as dimensions, orientation, and conductivity.
Hydraulic fracturing is a widely-used process for improving well productivity by placing or enhancing cracks or channels from a well bore a surrounding reservoir. This operation essentially is performed by injecting a fracturing fluid into a well bore penetrating a subterranean formation at a pressure sufficient to create a fracture in the formation or to enhance a natural fracture in the formation. Proppant particulates may be placed in the fracture to prevent the fracture from closing once the pressure is released. Upon placement, the proppant particulates usually form proppant packs in or near desired fractures. These proppant packs, thus, may maintain the integrity of those fractures to create conductive paths to the well bore for desirable fluids to flow. Placing an appropriate amount of proppant particulates to form a suitable proppant pack is thus important to the success of a hydraulic fracture treatment.
The geometry of a hydraulic fracture affects the efficiency of the process and the success of a fracturing operation. FIG. 1 illustrates basic fracture geometry. A fracture's geometry may be mapped from direct measurement of the fracture growth. This has been done, for instance, by placing tiltmeters in either the active well or in an observation well and monitoring rock deformation caused by the growing fracture. However, although tiltmeters and other direct methods (e.g., microseismic measurements) have been used to determine fracture geometry, historically, fracture geometry is more commonly estimated by interpreting measured data and applying mathematical models of fracture growth. This analysis has been generally limited to data from indirect measurements (e.g., flow rate, pressure, temperature, etc.) taken from the well bores during the fracture treatments. These measurements, however, are heavily influenced by well bore effects, such as fluid rheology, fluid density, and fluid friction in the well bore, and generally are not a reliable means of determining some fracture parameters. Fracture conditions, such as the integrity of the proppant pack over time and flow rates through various portions of the fracture pack, cannot be effectively monitored using these well bore measurements